Refresh copy on Frequency insight and add TimeHelper

Class to be used for simple timestamp based randomization
and still allow testing.
Modified hello thinkup insight to be random based on TimeHelper and updated tests.
Updated FrequencyInsight to use TimeHelper for randomization.
Breaks out text into helper function.
Remove duplicate names in the List Membership insight.
Only generate an interaction insight for more than one mention
Show the username instead of full_name when missing (InterestingFollowers)

Added test for new least likel followers.
Moved the seconds formatting function of the insight into the class.
Handle missing full_name in the _user template.